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Music downloads greener than buying CDs

iTunes = three billion miles saved

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Downloading digital music is better for the environment than buying physical CDs from a retail store or online etailer, according to a trio of researchers.

Their study (PDF), entitled The Energy and Climate Change Impacts of Different Music Delivery Methods and sponsored by Microsoft and Intel, details an exhaustive investigation into six different digital-music distribution and purchasing scenarios, ranging from traditional retail CD sales to digital downloads played on a computer or digital-media device.

To determine the carbon footprint and energy required for each scenario, the researchers took into account such factors as CD production and materials, packaging, air and surface shipping, data-center energy requirements, car trips to retail stores, the energy used in web shopping and music playing, and more.

Each assumption was assigned a data range, and the resulting uncertainties were subjected to probabilistic analysis using a Monte Carlo simulation.

As is true with any responsible scientific analysis, caveats abound in the paper, but the bottom line is clear. "Given our assumptions," it concludes, "our results indicate the superiority of downloadable online music, which even in the worst-case scenario produces on average 65 per cent lower CO2 emissions than the best-case e-tail delivery method. Significantly higher savings (nearly a factor of five) can be seen if the customer forgoes CD-R burning in favor of fully digital use, thereby eliminating the energy it took to produce the CD and its packaging."

The worst-case retail scenario - a customer driving to a retail store and buying a CD - produces an average of 3,200 grams of CO2 per album. The best-case digital-download scenario - a customer downloading a CD's worth of tunes and not burning them to a CD-R - produces an average of 400 grams of CO2.

Such data, of course, might beg the question: "So what?", so we pulled out our calculators, punched in a few numbers, and tallied up the CO2 emissions saved by Apple's iTunes Music Store.

In January of this year, Apple senior vice president for marketing Phil Schiller announced that six billion songs had been downloaded from the iTunes Store since it opened in 2003. Assuming 12 songs per album, that'd be the equivalent of 500 million CDs.

Five-hundred million physical CDs bought in retail stores would thus produce 1,600,000 metric tons of CO2. The same number of purely digital albums would produce one-eighth of that amount, namely 200,000 metric tons.

According to calculations developed by the US Environmental Protection Agency, the average US passenger vehicle - a mix of cars and light trucks - produces about 5.5 metric tons of CO2 per year of driving, which the EPA deems to average 12,000 miles.

By January of this year, therefore, the iTunes Music Store had reduced CO2 emissions equivalent to those produced by over three billion miles of driving, That's an impressive figure - until you learn that the EPA also estimates that Americans drive a total of over 2.4 trillion miles per year.

Still, every little bit helps when it comes to delaying Thermageddon. ®